大气C/O比对热木星内部的影响
The effect of the atmospheric C/O ratio on interiors of hot Jupiters
- Leiden University（莱顿大学）
- SRON Netherlands Institute for Space Research（荷兰空间研究所）
- Max Planck Institute for Astronomy（马克斯·普朗克天文学研究所）
机构由 AI 辅助整理，请以论文原文为准。
中文总结 AI 辅助
本文研究大气C/O比对热木星内部结构的影响，通过耦合一维大气模型与内部结构模型，发现高C/O比显著改变RCB温度与半径，强调需将大气成分与内部耦合考虑。
中文摘要 AI 辅助
大气是气态巨行星系外行星内部的外边界。因此，大气中的成分变化会影响内部推断。通常，在大气边界条件中仅考虑金属丰度，而其他元素比率，特别是C/O比，被假定为太阳值。鉴于JWST现在可实现的观测约束，这一假设可能不再合理。在这项工作中，我们研究了C/O比对热木星的大气边界条件、内部结构和半径的影响。我们构建了一个大气边界网格，由辐射-对流和热化学平衡下的一维大气模型组成。该网格在辐射-对流边界（RCB）处与静态内部结构模型耦合。因为在热木星的温度范围内，C/O比决定了大气中的主要物种，它可以显著改变不透明度，从而改变RCB处的压力和温度。这种温度变化传播到对流内部，从而影响计算出的半径。相对于太阳C/O大气，对于平衡温度$\gtrsim$ 1500 K且大气金属丰度超太阳的行星，半径差异显著超过观测到的3%的半径不确定性。作为示例，我们证明，对于WASP-19 b，较高的C/O比导致较高的推断内部温度。这些结果强调了将大气成分和内部结构视为耦合系统的重要性。随着大气约束的改善，将测量的C/O比纳入大气边界条件对于获得热木星内部的稳健推断是必要的。
英文摘要
The atmosphere is the outer boundary of a gas giant exoplanet's interior. Therefore, compositional changes in the atmosphere can affect interior inferences. Typically, only metallicity is considered in atmospheric boundary conditions, while other elemental ratios, in particular the C/O ratio, are assumed to be solar. In light of the observational constraints now achievable with JWST, this assumption might no longer be justified. In this work, we investigate the effect of the C/O ratio on atmospheric boundary conditions, interiors and radii of hot Jupiters. We construct an atmospheric boundary grid, consisting of one-dimensional atmospheric models in radiative-convective and thermochemical equilibrium. This grid is coupled to a static interior structure model at the radiative-convective boundary (RCB). Because in the temperature regime of hot Jupiters, the C/O ratio determines the dominant species in the atmosphere, it can significantly alter the opacity and, consequently, the pressure and temperature at the RCB. This temperature change propagates into the convective interior, thus affecting the calculated radius. The radius difference relative to a solar C/O-atmosphere significantly exceeds observed radius uncertainties of 3 per cent for planets with equilibrium temperatures $\gtrsim$ 1500 K and super-solar atmospheric metallicities. As an example, we demonstrate that, for WASP-19~b, higher C/O ratios result in higher inferred intrinsic temperatures. These results highlight the importance of treating atmospheric composition and interior structure as a coupled system. As atmospheric constraints improve, incorporating measured C/O ratios into atmospheric boundary conditions is necessary to obtain robust inferences of hot Jupiter interiors.
